Self-management of Type 1 diabetes mellitus (T1DM) worsens and diabetes control declines across adolescence. Adolescent autonomy development is an important factor in stimulating self-management. During middle adolescence cognitive development provides a unique opportunity for parents to enhance diabetes self- management by supporting adolescent autonomy. The purpose of this study is to further develop and pilot a parent-adolescent multifamily group psychoeducational Autonomy Support Program based on the Self-Determination Theory and previous research findings. The Autonomy Support Program will be refined based on feedback from 4 separate focus groups including (a) diabetes professionals, (b) parents, (c) adolescent boys and (d) adolescent girls with T1DM. A pilot randomized control trial of the Autonomy Support Program will then be implemented to 1) assess the feasibility of recruitment and retention, 2) assess intervention fidelity, and 3) provide preliminary estimates of efficacy of the intervention. For this phase, 48 adolescents between 15 and 17 years of age, who have T1DM, and their parent(s) will be enrolled;24 families will be randomly assigned to the Parental Autonomy Support Program, and 24 families will be randomly assigned to a placebo attention control. The intervention, delivered over 2 months consists of two in-person education-and- support workshops, written materials, and telephone follow-up education-and- support. Baseline and two follow-up assessments will be completed. Qualitative content analysis will be used to analyze transcripts of focus group interviews. General linear model analyses in SAS (GLM and MIXED procedures) will be used to examine the effects of: 1) time, 2) treatment, and 3) time by treatment interaction, and effect sizes will be calculated. It is anticipated that results from this pilot study will provide data needed to plan a larger more definitive randomized trial on the effect of a parent-adolescent multifamily group psychoeducational intervention on adolescent self-management, depressive symptomatology and diabetes control. Thesaurus Terms: Type 1 diabetes, adolescents, parents, multifamily group intervention, psychoeducational intervention, Self-Determination Theory, diabetes self-management. PUBLIC HEALTH RELEVANCE: The purpose of the proposed project is to refine, pilot, and assess the feasibility of a joint parent and adolescent (ages 15-17) psychoeducational multifamily group Autonomy Support Program to facilitate adolescent self-management of Type 1 diabetes and diabetes control in the transition from middle to late adolescence.